mungedb-aggregate/lib/index.js

"use strict";

/**
 * Used to aggregate `inputs` using a MongoDB-style `pipeline`
 *
 * If `inputs` is given, it will run the `inputs` through the `pipeline` and call the `callback` with the results.
 * If `inputs` is omitted, it will return an "aggregator" function so you can reuse the given `pipeline` against various `inputs`.
 *
 * NOTE: you should be mindful about reusing the same `pipeline` against disparate `inputs` because document coming in can alter the state of it's `DocumentSource`s
 *
 * @method aggregate
 * @namespace mungedb
 * @module mungedb-aggregate
 * @param pipeline  {Array}  The list of pipeline document sources in JSON format
 * @param [inputs]  {Array}  Optional inputs to pass through the `docSrcs` pipeline
 * @param [callback]               {Function}                                 Optional callback if using async extensions, called when done
 * @param   callback.err           {Error}                                    The Error if one occurred
 * @param   callback.docs          {Array}                                    The resulting documents
 **/
exports = module.exports = function aggregate(pipeline, inputs, callback) {	// function-style interface; i.e., return the utility function directly as the require
	var ctx = {}, //not used yet
		pipelineInst = exports.pipeline.Pipeline.parseCommand({
			pipeline: pipeline
		}, ctx),
		aggregator = function aggregator(inputs, callback) {
			if (!callback) callback = exports.SYNC_CALLBACK;
			if (!inputs) return callback("arg `inputs` is required");

			// rebuild the pipeline on subsequent calls
			if (!pipelineInst) {
				pipelineInst = exports.pipeline.Pipeline.parseCommand({
					pipeline: pipeline
				}, ctx);
			}

			// use or build input src
			try{
				ctx.ns = inputs;	//NOTE: use the given `inputs` directly; not really a "name" but we don't really have collection names in mungedb-aggregate
				exports.pipeline.PipelineD.prepareCursorSource(pipelineInst, ctx);
			}catch(err){
				return callback(err);
			}

			// run the pipeline against
			pipelineInst.stitch();
			var results = pipelineInst.run(callback === exports.SYNC_CALLBACK ? undefined : function aggregated(err, results){
				if(err) return callback(err);
				return callback(null, results.result);
			});
			pipelineInst = null; // unset so that subsequent calls can rebuild the pipeline
			return results ? results.result : undefined;
		};
	if(inputs) return aggregator(inputs, callback);
	return aggregator;
};

// sync callback for aggregate if none was provided
exports.SYNC_CALLBACK = function(err, docs){
	if (err) throw err;
	return docs;
};

// package-style interface; i.e., return a function underneath of the require
exports.aggregate = exports;

//Expose these so that mungedb-aggregate can be extended.
exports.Cursor = require("./Cursor");
exports.pipeline = require("./pipeline/");

// version info
exports.version = "r2.5.4";
exports.gitVersion = "ffd52e5f46cf2ba74ba931c78da62d4a7f480d8e";

// error code constants
exports.ERRORS = require('./Errors.js');